Alrighty so my Armalite M15 currently has the m4 style adjustable stock on it. I was gonna take that off and put on an A2 fixed stock that I have hangin around, but for some reason I can't get the castle nut to budge. Anyone know if Armalite uses any kinda thread locker on their lowers? Or is it just crazy tight? One o those things, I'd rather just leave it as is instead of screwin somethin upthanks dudes